Switching from originator to biosimilar infliximab - real world data of a prospective 18 months follow-up of a single-centre IBD population

Background and aims: Long-term data regarding switching from originator infliximab to biosimilar CT-P13 are sparse. Concerns about increased immunogenicity after switching have been raised. We aimed to study the effectiveness, safety and immunogenicity after switching from originator infliximab to CT-P13 in a real-world IBD population with 18 months prospective follow-up.Methods: All adult IBD patients treated with originator infliximab at the Department of Gastroenterology, Oslo University Hospital, were switched to CT-P13 and followed prospectively for 18 months.The primary endpoints were (i) the proportion of patients remaining on CT-P13 18 months after switching and (ii) immunogenicity during 18 months after switching. The secondary endpoints included (i) adverse events, (ii) changes in disease activity, C-reactive protein, anaemia, faecal calprotectin, infliximab dose and interval and p-infliximab.Results: In total, 143 IBD patients were switched, 99 with Crohn's disease and 44 with ulcerative colitis. Altogether, 130 (91%) remained on CT-P13 throughout 18 months.Two patients developed ADAs at moderate level and discontinued CT-P13. Another 10 patients discontinued CT-P13 (two due to loss of response without ADAs, four due to adverse events, and four in remission and a personal wish to stop).There was no overall change in disease activity scores or in the other studied variables except for p-infliximab, which increased significantly.Conclusions: The present study provides valuable evidence for the safety and effectiveness of switching from originator to biosimilar infliximab over a prolonged period of 18 months and demonstrates that switching was well tolerated and did not affect the long term clinical outcome.